Research On The Microstructure And Mechanical Properties Of (TIC+TIB) Reinforced High Temperature Titanium Matrix Composites

In situ synthesized high temperature titanium matrix composites with different fraction (0.5%,1%,2.5%,5%,7.5%,10%) of TiC and TiB were fabricated in this paper. 2.5vol.% composite were fabricated by induction skull melting, forging and heat treatment technology. The microstructure of composites and reinforcements were studied by SEM. Compression properties, bending properties at room temperature , tensile properties at room and high temperature were researched. The strengthening and fracture mechanism of the composite materials were discussed in this paper.Composites were fabricated by the reaction of B4C, C and Ti-6Al-3Sn- 4Zr-0.7Mo-0.3Si-0.3Y. The interface is clean. Matrix is a characteristic of lamellar. The shape of TiB is acicular or fibrous, the shap of TiC is equiaxial or dendritic. Compressive test at room temperature showed that the intensity increased but the plastic decreased with the fraction of reinforcement increased. Bending test showed that strength and ductility decreased with the increasing of the content of reinforcement. Study showed that 2.5vol.% composite have better properties.Titanium matrix composites with the volume fraction of 2.5% were prepared by ISM. The reinforcement distribute well in the matrix. The interface is clean. Matrix is a characteristic of lamellar. the shape of TiB is fibrous or lamellar, the shap of TiC is equiaxial. The tensile tests at room and high temperature showed that the strength of composite materials are highter than traditional high temperature titanium alloy, the strength reach to 1034 MPa, the elongation reach to 0.48%. Composite materials have good strength and elongation in high temperature. The strengthening mechanism of composite materials is the load transfer strengthening of TiC and TiB, solid solution strengthening and grain refinement.The reinforcements and matrix align after forge in the vertical orientation, and the structure is refined, but the structure is coarse in the forging orientation. The tensile test at room temperature show that the composites is stronger than casting composite about 150MPa respectively, elongation increase to 4.95%.Composite materials has good strength and elongation in high temperature Equiaxed microstructure is obtained after solution inαphase region and aging in low-temperature, bimodal microstructur is obtained after solution inα+βphase region and aging low-temperature, Basket organization is obtained after solution inβphase region and aging in low-temperature. Heat treatment did not change the shap of TiC and TiB. Tensile test in high temperature shows that bimodal microstructur offered better ductility, Equiaxed microstructure have highest strength.